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To prevent phase shifting of the data with respect to the clock when running the line at high speeds and long distances, use the dce-terminal-timing enable interface configuration command. If SCTE terminal timing is not available from the DTE, use no form of this command, which causes the DCE to use its own clock instead of SCTE from the DTE.
dce-terminal-timing enableSyntax Description
This command has no arguments or keywords.
Defaults
DCE uses its own clock.
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
On the Cisco 4000 router, you can specify the serial Network Interface Module timing signal configuration. When the board is operating as a DCE and the DTE provides terminal timing (SCTE or TT), the dce-terminal-timing enable command causes the DCE to use SCTE from the DTE.
Examples
The following example prevents phase shifting of the data with respect to the clock:
Router(config)# interface serial 0 Router(config-if)# dce-terminal-timing enable
To set a delay value for an interface, use the delay interface configuration command. To restore the default delay value, use the no form of this command.
delay tens-of-microseconds
Syntax Description
tens-of-microseconds Integer that specifies the delay in tens of microseconds for an interface or network segment. To see the default delay, use the show interfaces command.
Defaults
Default delay values may be displayed with the EXEC command show interfaces.
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Examples
The following example sets a 30,000-microsecond delay on serial interface 3:
Router(config)# interface serial 3 Router(config-if)# delay 3000
Related Commands
show interfaces Displays the statistical information specific to a serial interface.
Command
Description
Syntax Description
string Comment or a description (up to 80 characters) to help you remember what is attached to the interface.
Defaults
No description is added.
Command Modes
Controller configuration
Command History
10.3 This command was introduced. 11.3 This command was modified to include the CT3IP controller.
Release
Modification
Usage Guidelines
The description command is meant solely as a comment to be put in the configuration to help you remember what certain controllers are used for. The description affects the CT3IP and MIP interfaces only and appears in the output of the show controller t3, show controller e1, show controller t1, and more system:running-config EXEC commands.
Examples
The following example describes a 3174 controller:
Router(config)# controller t1 Router(config-controller)# description 3174 Controller for test lab
Related Commands
more Displays a specified file. show controllers e1 Displays information about the E1 links supported by the NPM (Cisco 4000) or MIP (Cisco 7500 series). Displays information about the T1 links. Displays information about the CT3IP on Cisco 7500 series routers.
Command
Description
To configure an interface to inform the system it is down when loopback is detected, use the down-when-looped interface configuration command.
down-when-loopedSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command is valid for HDLC or PPP encapsulation on serial and HSSI interfaces.
There is not a no form of this command.
Backup Interfaces
When an interface has a backup interface configured, it is often desirable that the backup interface be enabled when the primary interface is either down or in loopback. By default, the backup is only enabled if the primary interface is down. By using the down-when-looped command, the backup interface will also be enabled if the primary interface is in loopback.
Testing an Interface with the Loopback Command
If testing an interface with the loopback command, or by placing the DCE into loopback, down-when-looped should not be configured; otherwise, packets will not be transmitted out the interface that is being tested.
Examples
The following example configures interface serial 0 for HDLC encapsulation. It is then configured to let the system know that it is down when in loopback mode.
Router(config)# interface serial0 Router(config-if)# encapsulation hdlc Router(config-if)# down-when-looped
Related Commands
backup interface Configures an interface as a secondary or dial backup interface. Diagnoses equipment malfunctions between an interface and a device.
Command
Description
To specify the maximum allowable bandwidth used by the PA-E3 port adapter and PA-T3 port adapter, use the dsu bandwidth interface configuration command. To return to the default bandwidth, use the no form of this command.
dsu bandwidth kbps
Syntax Description
kbps Maximum bandwidth in the range of 22 kbps to 44736 kbps. The default values are:
Defaults
34010 kbps for PA-E3
44736 kbps for PA-T3
Command Modes
Interface configuration
Command History
11.1 CA This command was introduced.
Release
Modification
Usage Guidelines
The local interface configuration must match the remote interface configuration. For example, if you reduce the maximum bandwidth to 16000 on the local port, you must also do the same on the remote port.
The dsu bandwidth command reduces the bandwidth by padding the E3 and T3 frame.
To verify the data service unit (DSU) bandwidth configured on the interface, use the show controllers serial EXEC command.
Examples
The following example sets the DSU bandwidth to 16000 kbps on interface 1/0/0:
Router(config)# interface serial 1/0/0 Router(config-if)# dsu bandwidth 16000
Related Commands
Displays information that is specific to the interface hardware.
Command
Description
To specify the interoperability mode used by a PA-E3 port adapter or PA-T3 port adapter, use the dsu mode interface configuration command. To return to the default mode, use the no form of this command.
dsu mode {0 | 1 | 2}
Syntax Description
0 Sets the interoperability mode to 0. This is the default. Specify mode 0 to connect a PA-E3 port adapter to another PA-E3 port adapter or to a Digital Link DSU (DL3100). Use mode 0 to connect a PA-T3 port adapter to another PA-T3 port adapter or to a Digital Link DSU (DL3100). 1 Sets the interoperability mode to 1. Specify mode 1 to connect a PA-E3 port adapter or PA-T3 port adapter to a Kentrox DSU. 2 Sets the interoperability mode to 2. Specify mode 2 to connect a PA-T3 port adapter to a Larscom DSU.
Defaults
0
Command Modes
Interface configuration
Command History
11.1 CA This command was introduced.
Release
Modification
Usage Guidelines
The local interface configuration must match the remote interface configuration. For example, if you define the data service unit (DSU) interoperability mode as 1 on the local port, you must also do the same on the remote port.
You must know what type of DSU is connected to the remote port to determine if it interoperates with a PA-E3 port adapter or a PA-T3 port adapter. Use mode 0 to connect a PA-E3 port adapter to another PA-E3 port adapter or to a Digital Link DSU (DL3100). Use mode 0 to connect a PA-T3 port adapter to another PA-T3 port adapter or to a Digital Link DSU (DL3100). Use mode 1 to connect a PA-E3 port adapter or a PA-T3 port adapter to a Kentrox DSU. Use mode 2 to connect a PA-T3 port adapter to a Larscom DSU. The dsu mode command enables and improves interoperability with other DSUs.
The dsu mode command enables and improves interoperability with other DSUs.
To verify the DSU mode configured on the interface, use the show controller serial EXEC command.
Examples
The following example sets the DSU mode to 1 on interface 1/0/0:
Router(config)# interface serial 1/0/0 Router(config-if)# dsu mode 1
Related Commands
Displays information that is specific to the interface hardware.
Command
Description
On the Cisco 4000 series, you can specify the serial Network Processor Module timing signal configuration. When the board is operating as a DTE, use the dte-invert-txc interface configuration command to invert the TXC clock signal received from the DCE. If the DCE accepts SCTE from the DTE, use the no form of this command.
dte-invert-txcSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
9.1 This command was introduced.
Release
Modification
Usage Guidelines
Use this command if the DCE cannot receive SCTE from the DTE, the data is running at high speeds, and the transmission line is long. This prevents phase shifting of the data with respect to the clock.
On the Cisco 4000 series, you can specify the serial Network Processor Module timing signal configuration. When the board is operating as a DTE, the dte-invert-txc command inverts the TXC clock signal it gets from the DCE that the DTE uses to transmit data.
If the DCE accepts SCTE from the DTE, use no dte-invert-txc.
Examples
The following example inverts the TXC on serial interface 0:
Router(config)# interface serial 0 Router(config-if)# dte-invert-txc
To configure duplex operation on an interface, use the duplex interface configuration command. To return the system to half-duplex mode, the system default, use the no form of this command.
duplex {full | half | auto}
Syntax Description
full Specifies full-duplex operation. half Specifies half-duplex operation. This is the default. auto Specifies the autonegotiation capability. The interface automatically operates at half or full duplex, depending on environmental factors, such as the type of media and transmission speeds for the peer routers, hubs, and switches used in the network configuration.
Defaults
Half-duplex mode
Command Modes
Interface configuration
Command History
11.2(10)P This command was introduced.
Release
Modification
Usage Guidelines
To use the auto-negotiation capability (that is, detect speed and duplex modes automatically), you must set both speed and duplex to auto. Setting speed to autonegotiates speed only, and setting duplex to autonegotiates duplex only.
Table 9 describes the access server's performance for different combinations of the duplex and speed modes. The specified duplex command configured with the specified speed command produces the resulting system action.
| duplex Command | speed Command | Resulting System Action |
|---|---|---|
duplex auto | speed auto | Autonegotiates both speed and duplex modes. |
duplex auto | speed 100 or speed 10 | Autonegotiates both speed and duplex modes. |
duplex half or duplex full | speed auto | Autonegotiates both speed and duplex modes. |
duplex half | speed 10 | Forces 10 Mbps and half duplex. |
duplex full | speed 10 | Forces 10 Mbps and full duplex. |
duplex half | speed 100 | Forces 100 Mbps and half duplex. |
duplex full | speed 100 | Forces 100 Mbps and full duplex. |
For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the following two earlier duplex commands:
You will get the following error messages if you try to use these commands on a Cisco AS5300:
Router(config)# interface fastethernet 0 Router(config-if)# full-duplex Please use duplex command to configure duplex mode Router(config-if)# Router(config-if)# half-duplex Please use duplex command to configure duplex mode
Examples
The following example shows the different duplex configuration options you can configure on a Cisco AS5300:
Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)# interface fastethernet 0 Router(config-if)# duplex ? auto Enable AUTO duplex configuration full Force full duplex operation half Force half-duplex operation
Related Commands
Configures the duplex operation on an interface. Selects a particular Fast Ethernet interface for configuration. Displays information about initialization block information, transmit ring, receive ring, and errors for the Fast Ethernet controller chip on the Cisco 4500, Cisco 7200 series, or Cisco 7500 series routers. Configures the speed for a Fast Ethernet interface.
Command
Description
To configure the serial0 interface for E2 (8 Mhz full duplex) and to shut down the other three serial interfaces (1 to 3), use the e2-clockrate privileged EXEC command. To disable the full duplex E2, use the no form of this command.
e2-clockrateSyntax Description
There are no arguments or keywords used with this command.
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
12.0(2)XD This command was introduced. 12.0(3)T This command was modified.
Release
Modification
Usage Guidelines
The e2-clockrate privileged EXEC command is an interface configuration command and is seen only with interface serial0. When this command is used, serial interface 0 supports speeds up to E2 (8 MHz full duplex) and the other three serial interfaces (1 to 3) are put in "shutdown" state. Also, running this command displays the warning message, "Serial interface 0 is configured to support E2 rates and serial ports "1-3" are moved to shutdown state."
Examples
The following example shows sample display output for the e2-clockrate EXEC command.
Router(config-if)#e2-clockrateInterface Serial 0 is configured to support clockrates up to E2 (8Mbps)Interfaces serial 1-3 will not be operational
Related Commands
Configures the clock rate for the hardware connections on serial interfaces such as NIMs and interface processors to an acceptable bit rate.
Command
Description
To enable early token release on Token Ring interfaces, use the early-token-release interface configuration command. To disable this feature, use the no form of the command.
early-token-releaseSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Early token release is a method whereby the Token Ring interfaces can release the token back onto the ring immediately after transmitting, rather than waiting for the frame to return. This feature helps increase the total bandwidth of the Token Ring.
The Token Ring Interface Processor (TRIP) on the Cisco 7500 series routers and the Token Ring adapters on the Cisco 7200 series routers all support early token release.
Examples
The following example enables the use of early token release on Token Ring interface 1:
Router(config)# interface tokenring 1 Router(config-if)# early-token-release
On the Cisco 7500 series, to enable the use of early token release on your Token Ring interface processor in slot 4 on port 1, issue the following configuration commands:
Router(config)# interface tokenring 4/1 Router(config-if)# early-token-release
To set the encapsulation method used by the interface, use the encapsulation interface configuration command.
encapsulation encapsulation-type
Syntax Description
Defaults
The default depends on the type of interface. For example, synchronous serial interfaces default to HDLC and asynchronous interfaces default to SLIP.
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
To use SLIP or PPP, the router or access server must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.
On lines configured for interactive use, encapsulation is selected by the user when they establish a connection with the slip or ppp EXEC command.
IP Control Protocol (IPCP) is the part of PPP that brings up and configures IP links. After devices at both ends of a connection communicate and bring up PPP, they bring up the control protocol for each network protocol that they intend to run over the PPP link such as IP or IPX. If you have problems passing IP packets and the show interface command shows that line is up, use the negotiations command to see if and where the negotiations are failing. You might have different versions of software running, or different versions of PPP, in which case you might need to upgrade your software or turn off PPP option negotiations. All IPCP options as listed in RFC 1332, "PPP Internet Protocol Control Protocol (IPCP)," are supported on asynchronous lines. Only Option 2, TCP/IP header compression, is supported on synchronous interfaces.
PPP echo requests are used as keepalive packets to detect line failure. The no keepalive command can be used to disable echo requests. For more information about the no keepalive command, refer to the chapter "IP Services Commands" in the Networking Protocols Command Reference, Part 1 and the chapter "Configuring IP Services" in the Networking Protocols Configuration Guide, Part 1.
In order to use SLIP or PPP, the Cisco IOS software must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.
 |
Note Disable software flow control on SLIP and PPP lines before using the encapsulation command. |
There is not a no form of this command.
Examples
The following example resets HDLC serial encapsulation on serial interface 1:
Router(config)# interface serial 1 Router(config-if)# encapsulation hdlc
The following example enables PPP encapsulation on serial interface 0:
Router(config)# interface serial 0 Router(config-if)# encapsulation ppp
In the following example, async interface 1 is configured for PPP encapsulation.
Router# config Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z. Router(config)# interface async 1 Router(config-if)# encapsulation ppp
Related Commands
Specifies operation of a serial interface as an X.25 device. Sets the keepalive timer for a specific interface. ppp Starts an asynchronous connection using PPP. ppp authentication Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication are selected on the interface. ppp bap call Sets PPP BACP call parameters. slip Starts a serial connection to a remote host using SLIP.
Command
Description
To allow the FCI card to preallocate buffers to handle bursty FDDI traffic (for example, NFS bursty traffic), use the fddi burst-count interface configuration command. To revert to the default value, use the no form of this command.
fddi burst-count number
Syntax Description
number Number of preallocated buffers in the range from 1 to 10. The default is 3.
Defaults
3 buffers
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command applies to the FCI card only.
|
Note The microcode software version should not be 128.45 or 128.43. |
Examples
The following example sets the number of buffers to 5:
Router(config)# interface fddi 0 Router(config-if)# fddi burst-count 5
To set the C-Min timer on the PCM, use the fddi c-min interface configuration command. To revert to the default value, use the no form of this command.
fddi c-min microseconds
Syntax Description
microseconds Sets the timer value in microseconds. The default is 1600 microseconds.
Defaults
1600 microseconds
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command applies to the processor CMT only. You need extensive knowledge of the PCM state machine to tune this timer. Use this command when you run into PCM interoperability problems.
Examples
The following example sets the C-Min timer to 2000 microseconds:
Router(config)# interface fddi 0 Router(config-if)# fddi c-min 2000
Related Commands
Sets the TB-Min timer in the PCM. Controls the TL-Min time (the minimum time to transmit a PHY line state before advancing to the PCM state, as defined by the X3T9.5 specification). Sets the t-out timer in the PCM.
Command
Description
To control the information transmitted during the connection management (CMT) signaling phase, use the fddi cmt-signal-bits interface configuration command.
fddi cmt-signal-bits signal-bits [phy-a | phy-b]
Syntax Description
signal-bits A hexadecimal number preceded by 0x; for example, 0x208. The FDDI standard defines 10 bits of signaling information that must be transmitted, as follows: phy-a (Optional) Selects Physical Sublayer A. The default is 0x008 (hexadecimal) or 00 0000 1000 (binary). Bits 1 and 2 are set to 00 to select Physical A. Bit 3 is set to 1 to indicate "accept any connection." phy-b (Optional) Selects Physical Sublayer B. The default is 0x20c (hexadecimal) or 10 0000 1100 (binary). Bits 1 and 2 are set to 10 to select Physical B. Bit 3 is set to 1 to indicate "accept any connection." Bit 9 is set to 1 to select MAC on output. The normal data flow on FDDI is input on Physical A and output on Physical B.
Defaults
The default signal bits for the phy-a and phy-b keywords are as follows:
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
If neither the phy-a nor phy-b keyword is specified, the signal bits apply to both physical connections.
 |
Caution Use of the fddi cmt-signal-bits configuration command is not recommended under normal operations. This command is used when debugging specific CMT implementation issues. |
Table 10 lists the physical types.
| Bit 2 | Bit 1 | Physical Type |
|---|---|---|
0 | 0 | Physical A |
1 | 0 | Physical B |
0 | 1 | Physical S |
1 | 1 | Physical M |
Table 11 lists the duration bits.
| Bit 5 | Bit 4 | Test Duration |
|---|---|---|
0 | 0 | Short test (default 50 ms) |
1 | 0 | Medium test (default 500 ms) |
0 | 1 | Long test (default 5 seconds) |
1 | 1 | Extended test (default 50 seconds) |
There is not a no form of this command.
Examples
The following example sets the CMT signaling phase to signal bits 0x208 on both physical connections:
Router(config)# interface fddi 0 Router(config-if)# fddi cmt-signal-bits 208
To turn on the duplicate address detection capability on the FDDI, use the fddi duplicate-address-check interface configuration command. To disable this feature, use the no form of this command.
fddi duplicate-address-checkSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
If you use this command, the Cisco IOS software will detect a duplicate address if multiple stations are sharing the same MAC address. If the software finds a duplicate address, it will shut down the interface.
Examples
The following example enables duplicate address checking on the FDDI:
Router(config)# interface fddi 0 Router(config-if)# fddi duplicate-address-check
To specify encapsulating bridge mode on the CSC-C2/FCIT interface card, use the fddi encapsulate interface configuration command. To turn off encapsulation bridging and return the FCIT interface to its translational, nonencapsulating mode, use the no form of this command.
fddi encapsulateSyntax Description
This command has no arguments or keywords.
Defaults
The FDDI interface by default uses the SNAP encapsulation format defined in RFC 1042, "Standard for the Transmission of IP Datagrams Over IEEE 802 Networks." It is not necessary to define an encapsulation method for this interface when using the CSC-FCI interface card.
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
The no fddi encapsulate command applies only to CSC-C2/FCIT interfaces, because the CSC-FCI interfaces are always in encapsulating bridge mode. The CSC-C2/FCIT interface card fully supports transparent and translational bridging for the following configurations:
The command fddi encapsulate puts the CSC-C2/FCIT interface into encapsulation mode when doing bridging. In transparent mode, the FCIT interface interoperates with earlier versions of the CSC-FCI encapsulating interfaces when performing bridging functions on the same ring.
|
Caution Bridging between dissimilar media presents several problems that can prevent communications from occurring. These problems include bit-order translation (or usage of MAC addresses as data), maximum transfer unit (MTU) differences, frame status differences, and multicast address usage. Some or all of these problems might be present in a multimedia bridged LAN and might prevent communication from taking place. These problems are most prevalent when bridging between Token Rings and Ethernets or between Token Rings and FDDI nets. This is because of the different way Token Ring is implemented by the end nodes. |
The following protocols have problems when bridged between Token Ring and other media: Novell IPX, DECnet Phase IV, AppleTalk, VINES, XNS, and IP. Further, the following protocols may have problems when bridged between FDDI and other media: Novell IPX and XNS. We recommend that these protocols be routed whenever possible.
Examples
The following example sets FDDI interface 1 on the CSC-C2/FCIT interface card to encapsulating bridge mode:
Router(config)# interface fddi 1 Router(config-if)# fddi encapsulate
To specify the maximum number of frames that the FDDI interface will transmit per token capture, use the fddi frames-per-token interface configuration command. To revert to the default values, use the no form of this command.
fddi frames-per-token number
Syntax Description
number Maximum number of frames to transmit per token capture. Valid values are from 1 to 10. The default is 3.
Defaults
3 frames
Command Modes
Interface configuration
Command History
11.2 P This command was introduced.
Release
Modification
Usage Guidelines
Changing the value will increase or decrease the maximum number of frames that the FDDI interface can transmit when it receives a token. Increasing the value does not necessarily mean more frames will be transmitted on each token capture. This is heavily dependent on the traffic load of the specific interface.
When the interface captures a token, it transmits all of the frames that are queued in the interface's transmit ring, up to a maximum value specified by the fddi frames-per-token command.
If there are no frames ready for transmission, the token is passed on, and no frames are transmitted. If there are less than the fddi frames-per-token value in the transmit ring, all frames in the transmit ring are transmitted before the token is passed on. If there are more than the fddi frames-per-token value in the transmit ring, the specified value is transmitted before the token is passed on. The remaining frames in the transmit ring remain queued until the token is captured again.
Examples
The following example shows how to configure the FDDI interface to transmit four frames per token capture:
! Show fddi frames-per-token command options 4700(config-if)#fddi frames-per-token ? <1-10> Number of frames per token, default = 3 ! Specify 4 as the maximum number of frames to be transmitted per token 4700(config-if)#fddi frames-per-token 4
To enable the SMT frame processing capability on the FDDI, use the fddi smt-frames interface configuration command. To disable this function and prevent the Cisco IOS software from generating or responding to SMT frames, use the no form of this command.
fddi smt-framesSyntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Use the no form of this command to turn off SMT frame processing for diagnosing purposes. Use the fddi smt-frames command to reenable the feature.
Examples
The following example disables SMT frame processing:
Router(config)# interface fddi 0 Router(config-if)# no fddi smt-frames
To set the TB-Min timer in the physical connection management (PCM), use the fddi tb-min interface configuration command. To revert to the default value, use the no form of this command.
fddi tb-min milliseconds
Syntax Description
milliseconds Number that sets the TB-Min timer value. The range is 0 to 65,535 ms. The default is 100 ms.
Defaults
100 ms
Command Modes
Interface configuration
Command History
10.3 This command was introduced.
Release
Modification
Usage Guidelines
This command applies to the processor CMT only. Use this command when you run into PCM interoperability problems.
|
Note You need extensive knowledge of the PCM state machine to tune this timer. |
Examples
The following example sets the TB-Min timer to 200 ms:
Router(config)# interface fddi 0 Router(config-if)# fddi tb-min 200
Related Commands
Sets the C-Min timer on the PCM. Controls the TL-Min time (the minimum time to transmit a PHY line state before advancing to the PCM state, as defined by the X3T9.5 specification). Sets the t-out timer in the PCM.
Command
Description
Syntax Description
microseconds Number that specifies the time used during the connection management (CMT) phase to ensure that signals are maintained for at least the value of TL-Min so the remote station can acquire the signal. The range is 0 to 4,294,967,295 microseconds. The default is 30 microseconds.
Defaults
30 microseconds
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Interoperability tests have shown that some implementations of the FDDI standard need more than 30 microseconds to sense a signal.
There is not a no form of this command.
Examples
The following example changes the TL-Min time from 30 microseconds to 100 microseconds:
Router(config)# interface fddi 0 Router(config-if)# fddi tl-min-time 100
The following example changes the TL-Min time from 30 microseconds to 100 microseconds on a Cisco 7500 series router:
Router(config)# interface fddi 3/0 Router(config-if)# fddi tl-min-time 100
Related Commands
Sets the C-Min timer on the PCM. Controls the TL-Min time (the minimum time to transmit a PHY line state before advancing to the PCM state, as defined by the X3T9.5 specification). Sets the t-out timer in the PCM.
Command
Description
To set the t-out timer in the physical connection management (PCM), use the fddi t-out interface configuration command. To revert to the default value, use the no form of this command.
fddi t-out milliseconds
Syntax Description
milliseconds Number that sets the timeout timer. The range is 0 to 65,535 ms. The default is 100 ms.
Defaults
100 ms
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
This command applies to the processor CMT only. Use this command when you run into PCM interoperability problems.
|
Note You need extensive knowledge of the PCM state machine to tune this timer. |
Examples
The following example sets the timeout timer to 200 ms:
Router(config)# interface fddi 0 Router(config-if)# fddi t-out 200
Related Commands
Sets the C-Min timer on the PCM. Sets the TB-Min timer in the PCM. Controls the TL-Min time (the minimum time to transmit a PHY line state before advancing to the PCM state, as defined by the X3T9.5 specification).
Command
Description
To control ring scheduling during normal operation and to detect and recover from serious ring error situations, use the fddi token-rotation-time interface configuration command. To revert to the default value, use the no form of this command.
fddi token-rotation-time microseconds
Syntax Description
microseconds Number that specifies the token rotation time (TRT). The range is 4000 to 165,000 microseconds. The default is 5000 microseconds.
Defaults
5000 microseconds
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
The FDDI standard restricts the allowed time to be greater than 4000 microseconds and less than 165,000 microseconds. As defined in the X3T9.5 specification, the value remaining in the TRT is loaded into the token holding timer (THT). Combining the values of these two timers provides the means to determine the amount of bandwidth available for subsequent transmissions.
Examples
The following example sets the rotation time to 24,000 microseconds:
Router(config)# interface fddi 0 Router(config-if)# fddi token-rotation-time 24000
The following example sets the rotation time to 24,000 microseconds on a Cisco 7500 series router:
Router(config)# interface fddi 3/0 Router(config-if)# fddi token-rotation-time 24000
To recover from a transient ring error, use the fddi valid-transmission-time interface configuration command. To revert to the default value, use the no form of this command.
fddi valid-transmission-time microseconds
Syntax Description
microseconds Number that specifies the transmission valid timer (TVX) interval. The range is 2500 to 2,147,483,647 microseconds. The default is 2500 microseconds.
Defaults
2500 microseconds
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
None.
Examples
The following example changes the transmission timer interval to 3000 microseconds:
Router(config)# interface fddi 0 Router(config-if)# fddi valid-transmission-time 3000
The following example changes the transmission timer interval to 3000 microseconds on a Cisco 7000 series routers or Cisco 7200 series routers:
Router(config)# interface fddi 3/0 Router(config-if)# fddi valid-transmission-time 3000
To set the Facility Data Link (FDL) exchange standard for the CSU controllers, or to set the FDL exchange standard for a T1 interface that uses Extended Super Frame (ESF) framing format, enter the fdl controller configuration or ATM interface configuration command. To disable FDL support or to specify that there is no ESF FDL, use the no form of this command.
Cisco MC3810 Multiservice Access Concentrator
fdl {att | ansi | both}
no fdl {att | ansi | both}
Cisco 2600 or 3600 Series Routers
fdl {att | ansi | all | none}
no fdl {att | ansi | all | none}
Syntax Description
att Selects AT&T technical reference 54016 for ESF FDL exchange support. ansi Selects ANSI T1.403 for ESF FDL exchange support. both Specifies support both AT&T technical reference 54016 and ANSI T1.403 for ESF FDL exchange support. all Specifies support for both AT&T technical reference 54016 and ANSI T1.403 for ESF FDL exchange support. none Specifies that there is no support for ESF FDL exchange.
Defaults
Disabled on the Cisco MC3810 multiservice access concentrator.
The default value is ansi on Cisco 2600 or 3600 series routers.
Command Modes
Controller configuration for the Cisco MC3810 multiservice access concentrator.
ATM interface configuration for the Cisco 2600 or 3600 series routers.
Command History
11.3 This command was introduced. 12.0 This command was modified to add command syntax both for the Cisco MC3810. 12.0(5)T and 12.0(5)XK The command was introduced as an ATM interface configuration command for the Cisco 2600 and 3600 series. The keyword none was added to the original controller command, and the keyword both was changed to all.
Release
Modification
Usage Guidelines
Cisco MC3810 Multiservice Access Concentrator
You must configure this command on both T1 controllers if you want to support the CSU function on each T1 line. However, you must use the same facilities data link exchange standard as your service provider. You can have a different standard configured on each T1 controller.
Cisco 2600 or 3600 Series Routers
This command is available for T1 links only and sets the standard that will be followed for FDL messaging through a 4-Kbps out-of-band channel that a service provider uses to check for errors on the facility. You must use the same FDL exchange standard as your service provider. If the setting is not correct, the link may fail to come up. You can have a different standard configured on each T1 interface.
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Note When using a multiport T1 ATM IMA network module on a Cisco 2600 or 3600 series router, ESF framing and binary eight zero substitution (B8ZS) line encoding are supported. When using a multiport E1 ATM IMA network module on a Cisco 2600 or 3600 series router, CRC4 multiframe framing and HDB3 line encoding are supported. These are the parameters specified by the ATM Forum, and they cannot be changed. |
Examples
Cisco MC3810 Multiservice Access Concentrator
The following example configures the ANSI T1.403 standard for both T1 controllers:
Router(config)# controller t1 0 Router(config-controller)# fdl ansi Router(config-controller)# exit Router(config)# controller t1 1 Router(config-controller)# fdl ansi
Cisco 2600 or 3600 Series Routers
In a Cisco 2600 or 3600 series router, the following example specifies both ANSI and AT&T standards for FDL exchange:
Router(config)# interface atm 0/2 Router(config-if)# fdl all
To configure Frame Relay payload compression for each Frame Relay port, use the frame-relay interface configuration command. To terminate this form of payload compression over Frame Relay, use the no form of this command.
frame-relay payload-compression frf9 stac caim [element-number]
Syntax Description
payload-compression Packet-by-packet payload compression, using the Stacker method. frf9 stac Enables FRF.9 compression using the Stacker method. If the router contains a data compression Advanced Interface Module (AIM) for the Cisco 2600 series router, compression is performed in the hardware (hardware compression). If the CAIM is not available, compression is performed in the software installed on the router's main processor (software compression). caim element-number (Optional) Enable the data compression AIM hardware compression daughtercard to do compression, at the element numbered beginning with 0 and incrementing to include all possible elements.
Defaults
Disabled
Command Modes
Interface configuration
Command History
12.0(2)T This command was introduced.
Release
Modification
Usage Guidelines
Use the frame-relay payload-compression command to enable or disable payload compression on a point-to-point interface or subinterface. Use the frame-relay map command to enable or disable payload compression on a multipoint interface or subinterface.
Shut down the interface prior to changing encapsulation types. Although this is not required, shutting down the interface ensures the interface is reset for the new encapsulation.
Examples
The following example shows Frame Relay configured to use payload compression with the frf9 stac algorithm for CAIM hardware compression, using the installed data compression Advanced Interface Module (AIM) daughtercard as the compression source:
Router(config-if)# frame-relay payload-compression frf9 stac caim 0
Related Commands
Specifies the exact hardware compression resource preferred. encapsulation frame-relay Enables Frame Relay encapsulation. frame-relay interface-dlci Assigns a DLCI to a specified Frame Relay subinterface on the router or access server. Displays compression statistics.
Command
Description
To enable Frame Relay compression on a DLC basis, enter the frame-relay map interface configuration command. To deactivate Frame Relay compression, use the no form of this command.
frame-relay map {protocol protocol-address dlci} payload-compression frf9 stac caim [element-number]
Syntax Description
map Defines mapping between a destination protocol address and the DLCI used to connect to the destination address. protocol Supported protocol, bridging, or logical link control keywords: appletalk, decnet, dlsw, ip, ipx, llc2, rsrb, vines and xns. protocol-address Destination protocol address. dlci DLCI number used to connect to the specified protocol address on the interface. payload-compression Packet-by-packet payload compression, using the Stacker method. frf9 Data compression over Frame Relay. stac Specifies that a Stacker (LZS) compression algorithm will be used on LAPB, HDLC, and PPP encapsulation. Compression is implemented in the hardware Advanced Interface Module installed in the router. caim Enables the data compression AIM hardware compression daughtercard to do compression. element-number (Optional) Compression element number, beginning with 0 and including all possible elements.
Defaults
Disabled
Command Modes
Interface configuration
Command History
12.0(1)T This command was introduced.
Release
Modification
Usage Guidelines
Many DLCIs known by an access server can be used to send data to many different places, but they are all multiplexed over one physical link. The Frame Relay map tells the Cisco IOS software how to get from a specific protocol and address pair to the correct DLCI.
Although you did not specified the IETF keyword during configuration, the map inherits the attributes set with the encapsulation frame-relay command so that all interfaces use IETF encapsulation.
Use the frame-relay map command to enable or disable payload compression on multipoint interfaces. Use the frame-relay payload-compression command to enable or disable payload compression on point-to-point interfaces.
The broadcast keyword provides two functions: It forwards broadcasts when multicasting is not enabled, and it simplifies the configuration of OSPF for nonbroadcast networks that will use Frame Relay.
The broadcast keyword might also be required for some routing protocols---for example, AppleTalk---that depend on regular routing table updates, especially when the router at the remote site is waiting for a routing update packet to arrive before adding the route. Network broadcasts are necessary if you intend to use routing protocols such as RIP or OSPF running across the Frame Relay link.
The frame-relay map payload-compression frf9 stac caim 0 command enables compression on the Frame Relay link, but requires the caim 0 portion of the command. To display Frame Relay output, do not use the show compress command; use the show controllers serial 0/0 command.
Examples
The following example shows configuration of the frame-relay map payload-compression command using the data compression AIM daughtercard for compression mapping the destination address 1.1.1.2 to DLCI 16:
Router(config-if)#frame-relay map ip 1.1.1.2 16 broadcast payload-compression frf9 stac caim 0
Related Commands
Specifies the exact hardware compression resource preferred. encapsulation frame-relay Enables Frame Relay encapsulation. frame-relay interface-dlci Assigns a DLCI to a specified Frame Relay subinterface on the router or access server. frame-relay payload-compress Enables Stacker payload compression on a specified point-to-point interface or subinterface. show controllers serial Displays information that is specific to the interface hardware.
Command
Description
To select the frame type for the E1 or T1 data line, use the framing controller configuration command.
T1 Lines
framing {sf | esf}
E1 Lines
framing {crc4 | no-crc4} [australia]
Syntax Description
sf Specifies super frame as the T1 frame type. This is the default. esf Specifies extended super frame as the T1 frame type. crc4 Specifies CRC4 frame as the E1 frame type. This is the default for Australia. no-crc4 Specifies no CRC4 frame as the E1 frame type. australia (Optional) Specifies the E1 frame type used in Australia.
Defaults
Super frame is the default on a T1 line.
CRC4 frame is the default on an E1 line.
Command Modes
Controller configuration
Usage Guidelines
Use this command in configurations where the router or access server is intended to communicate with T1 or E1 fractional data line. The service provider determines the framing type (sf, esf, or crc4) required for your T1/E1 circuit.
There is not a no form of this command.
Examples
The following example selects extended super frame as the T1 frame type:
Router(config-controller)# framing esf
Related Commands
Specifies the distance of the cable from the routers to the network equipment. Selects the linecode type for T1 or E1 line.
Command
Description
To specify E3 or T3 line framing for a PA-E3 port adapter or PA-T3 port adapter, use the framing interface configuration command. To return to the default G.751 framing or C-bit framing, use the no form of this command.
PA-E3
framing {bypass | g751}
no framing
PA-T3
framing {c-bit | m13 | bypass}
no framing
Syntax Description
bypass Specifies bypass E3 framing. g751 Specifies G.751 E3 framing. This is the default for the PA-E3. c-bit Specifies that the C-bit framing is used as the T3 framing type. This is the default for the PA-T3. m13 Specifies m13 T3 framing.
Defaults
G.751 framing for PA-E3
C-bit framing for PA-T3
Command Modes
Interface configuration
Command History
11.1 CA This command was introduced.
Release
Modification
Usage Guidelines
The default framing is described in the ITU-T Recommendation G.751.
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Note The ITU-T carries out the functions of the former Consultative Committee for International Telegraph and Telephone (CCITT). |
When the framing mode is bypass, the E3 frame data is not included in the E3 frame, just the data.
When the framing mode is bypass, the T3 frame data is not included in the T3 frame, just the data.
If you use the bypass option, scrambling must be set to the default (disabled), the dsu mode must be set to the default (0), and the dsu bandwidth must be set to the default (44736).
To verify the framing mode configured on the interface, use the show controller serial EXEC command.
Examples
The following example sets the framing mode to bypass on interface 1/0/0:
Router(config)# interface serial 1/0/0 Router(config-if)# framing bypass
Related Commands
Displays information that is specific to the interface hardware.
Command
Description
To specify T3 line framing used by the CT3 feature board in a Cisco AS5800 universal access server, or by the CT3IP port adapter in Cisco 7500 series routers, use the framing controller configuration command. To restore the default framing type, use the no form of this command.
Cisco AS5800 universal access server
framing {c-bit | m23}
no framing
Cisco 7500 series routers
framing {c-bit | m23 | auto-detect}
no framing
Syntax Description
c-bit Specifies that C-bit framing is used as the T3 framing type. This is the default for the CT3 in a Cisco AS5800. m23 Specifies that M23 framing is used as the T3 framing type. auto-detect Specifies that the CT3IP detects the framing type it receives from the far-end equipment. This is the default for the CT3IP in a Cisco 7500 series router.
Defaults
C-bit for CT3 in a Cisco AS5800
Auto-detect for CT3IP in a Cisco 7500 series router
Command Modes
Controller configuration
Command History
11.1 CA This command was introduced.
Release
Modification
Usage Guidelines
Because the CT3IP supports the Application Identification Channel (AIC) signal, the setting for the framing might be overridden by the CT3IP firmware.
You can also set the framing for each T1 channel by using the t1 framing controller configuration command.
Examples
The following example sets the framing for the CT3IP to C-bit:
Router(config)# controller t3 9/0/0 Router(config-controller)# framing c-bit
Related Commands
Specifies the type of framing used by the T1 channels on the CT3IP in Cisco 7500 series routers.
Command
Description
To specify full-duplex mode on full-duplex single-mode and multimode port adapters, use the full-duplex interface configuration command. To restore the default half-duplex mode, use the no form of this command.
full-duplexSyntax Description
This command has no arguments or keywords.
Defaults
Half-duplex mode is the default mode on a Cisco 7500 series router, a FEIP, and for serial interfaces that are configured for bisynchronous tunneling.
Command Modes
Interface configuration
Command History
11.1 This command was introduced. 11.3 This command was modified to include information on FDDI full-duplex, single-mode and multimode port adapters.
Release
Modification
Usage Guidelines
Use this command if the equipment on the other end is capable of full-duplex mode.
This command specifies full-duplex mode on full-duplex single-mode and multimode port adapters available on the following routers:
Refer to the Cisco Product Catalog for hardware compatibility information and for specific model numbers of port adapters.
To enable half-duplex mode, use the no full-duplex or half-duplex commands.
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Caution For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the full-duplex and half-duplex commands. You will get the following error messages if you try to use the full-duplex and half-duplex command on a Cisco AS5300: Router(config)# interface fastethernet 0 Router(config-if)# full-duplex Please use duplex command to configure duplex mode Router(config-if)# Router(config-if)# half-duplex Please use duplex command to configure duplex mode |
Support for this Command
Use the question mark (?) command to find out which port adapters support this command. If the interface does not support full-duplex, an informational message similar to the one shown below is displayed, and no changes are made to the interface. To determine if the interface supports full-duplex, use the show interfaces command. For example, the following message is displayed if the interface does not support full-duplex:
% interface does not support full-duplex.
Use on FDDI
Full-duplex autoconfiguration protocol allows an FDDI station to dynamically and automatically operate in either half-duplex (or ring) or full-duplex mode, and ensures that the stations fall back to ring mode when a configuration change occurs, such as a third station joining the ring.
After booting up, the FDDI stations begin operation in half-duplex mode. While the station performs the full-duplex autoconfiguration protocol, the station continues to provide data-link services to its users. Under normal conditions, the transition between half-duplex mode and full-duplex mode is transparent to the data-link users. The data-link services provided by full-duplex mode are functionally the same as the services provided by half-duplex mode.
If you change the full-duplex configuration (for example from disabled to enabled) on supported interfaces, the interface resets.
Examples
The following example configures full-duplex mode on the Cisco 7000 series routers:
Router(config)# interface fastethernet 0/1 Router(config-if)# full-duplex
The following example specifies full-duplex binary synchronous communications (Bisync) mode:
Router(config)# interface serial 0 Router(config-if)# encapsulation bstun Router(config-if)# full-duplex
The following example enables full-duplex mode on FDDI interface 0:
Router(config)# interface fddi 0/1/0 Router(config-if)# full-duplex
Related Commands
Specifies half-duplex mode on an SDLC interface or on the FDDI full-duplex, single-mode port adapter and FDDI full-duplex, multimode port adapter on the Cisco 7200 series and Cisco 7500 series routers. Configures an interface type and enters interface configuration mode. Selects a particular Fast Ethernet interface for configuration. interface serial Specifies a serial interface created on a channelized E1 or channelized T1 controller (for ISDN PRI, CAS, or robbed-bit signaling). Displays statistics for all interfaces configured on the router or access server. Displays information about the FDDI interface.
Command
Description
To specify half-duplex mode on an SDLC interface or on the FDDI full-duplex, single-mode port adapter and FDDI full-duplex, multimode port adapter on the Cisco 7200 series and Cisco 7500 series routers, use the half-duplex interface configuration command. Refer to the Cisco Product Catalog for specific model numbers of port adapters. To reset the interface for full-duplex mode, use the no form of this command.
half-duplexSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
11.1 This command was introduced. 11.3 This command was modified to include information on FDDI full-duplex, single-mode and multimode port adapters.
Release
Modification
Usage Guidelines
SDLC Interfaces
The half-duplex command is used to configure an SDLC interface for half-duplex mode and is used on a variety of port adapters. Use the question mark (?) command to find out which port adapters support this command.
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Note The half-duplex command replaces the sdlc hdx and media-type half-duplex commands. |
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Caution For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the full-duplex and half-duplex commands. You will get the following error messages if you try to use the full-duplex and half-duplex command on a Cisco AS5300: Router(config)# interface fastethernet 0 Router(config-if)# full-duplex Please use duplex command to configure duplex mode Router(config-if)# Router(config-if)# half-duplex Please use duplex command to configure duplex mode |
Enable Full-Duplex Mode
To enable full-duplex mode, use the no half-duplex or full-duplex commands.
|
Note The media-type half-duplex command exists in Cisco IOS Release 11.0(5). As of Release 11.0(6), the keyword half-duplex was removed from the media-type command. In Release 11.0(6), the functionality for specifying half-duplex mode is provided by the half-duplex command. |
Examples
The following example configures an SDLC interface for half-duplex mode:
Router(config-if)# encapsulation sdlc-primary Router(config-if)# half-duplex
Related Commands
Specifies full-duplex mode on full-duplex single-mode and multimode port adapters.
Command
Description
To place a low-speed serial interface in controlled-carrier mode, instead of constant-carrier mode, use the half-duplex controlled-carrier interface configuration command. To return the interface to constant-carrier mode, use the no form of this command.
half-duplex controlled-carrierSyntax Description
This command has no arguments or keywords.
Defaults
Constant-carrier mode, where DCD is held constant and asserted by the DCE half-duplex interface.
Command Modes
Interface configuration
Command History
11.2 This command was introduced.
Release
Modification
Usage Guidelines
This command applies only to low-speed serial DCE interfaces in half-duplex mode. Configure a serial interface for half-duplex mode by using the media-type half-duplex command. These interfaces are available on the following Cisco High Density Serial Routers: 2520, 2521, 2522, and 2523.
Controlled-carrier operation means that the DCE interface has DCD deasserted in the quiescent state. When the interface has something to transmit, it asserts DCD, waits a user-configured amount of time, then starts the transmission. When the interface has finished transmitting, it waits a user-configured amount of time and then deasserts DCD.
Examples
The following examples place the interface in controlled-carrier mode and back into constant-carrier operation.
Changing to controlled-carrier mode from the default of constant-carrier operation:
Router(config)# interface serial 2 Router(config-if)# half-duplex controlled-carrier
Changing to constant-carrier operation from controlled-carrier mode:
Router(config)# interface serial 2 Router(config-if)# no half-duplex controlled-carrier
Related Commands
Tunes half-duplex timers. Specifies the mode of a slow-speed serial interface on a router as either synchronous or asynchronous.
Command
Description
To tune half-duplex timers, use the half-duplex timer interface configuration command. To return to the default value for that parameter, use the no form of this command along with the appropriate keyword.
half-duplex timer {cts-delay value | cts-drop-timeout value | dcd-drop-delay value | dcd-txstart-delay value | rts-drop-delay value | rts-timeout value | transmit-delay value}
Syntax Description
cts-delay value Specifies the delay introduced by the DCE interface between the time it detects RTS to the time it asserts CTS in response. The range is dependent on the serial interface hardware. The default cts-delay value is 0 ms. cts-drop-timeout value Determines the amount of time a DTE interface waits for CTS to be deasserted after it has deasserted RTS. If CTS is not deasserted during this time, an error counter is incremented to note this event. The range is 0 to 1140000 ms (1140 seconds). The default cts-drop-timeout value is 250 ms. dcd-drop-delay value Applies to DCE half-duplex interfaces operating in controlled-carrier mode (see the half-duplex controlled-carrier command). This timer determines the delay between the end of transmission by the DCE and the deassertion of DCD. The range is 0 to 4400 ms (4.4 seconds). The default dcd-drop-delay value is 100 ms. dcd-txstart-delay value Applies to DCE half-duplex interfaces operating in controlled-carrier mode. This timer determines the time delay between the assertion of DCD and the start of data transmission by the DCE interface. The range is 0 to 1140000 ms (1140 seconds). The default dcd-txstart-delay value is 100 ms. rts-drop-delay value Specifies the time delay between the end of transmission by the DTE interface and deassertion of RTS. The range is 0 to 1140000 ms (1140 seconds). The default rts-drop-delay value is 3 ms. rts-timeout value Determines the number of milliseconds the DTE waits for CTS to be asserted after the assertion of RTS before giving up on its transmission attempt. If CTS is not asserted in the specified amount of time, an error counter is incremented. The range is dependent on the serial interface hardware. The default rts-timeout value is 3 ms. transmit-delay value Specifies the number of milliseconds a half-duplex interface will delay the start of transmission. In the case of a DTE interface, this delay specifies how long the interface waits after something shows up in the transmit queue before asserting RTS. For a DCE interface, this dictates how long the interface waits after data is placed in the transmit queue before starting transmission. If the DCE interface is in controlled-carrier mode, this delay shows up as a delayed assertion of DCD. This timer enables the transmitter to be adjusted if the receiver is a little slow and is not able to keep up with the transmitter. The range is 0 to 4400 ms (4.4 seconds). The default transmit-delay value is 0 ms.
Defaults
The default cts-delay value is 0 ms.
The default cts-drop-timeout value is 250 ms.
The default dcd-drop-delay value is 100 ms.
The default dcd-txstart-delay value is 100 ms.
The default rts-drop-delay value is 3 ms.
The default rts-timeout value is 3 ms.
The default transmit-delay value is 0 ms.
Command Modes
Interface configuration
Command History
11.3 This command was introduced.
Release
Modification
Usage Guidelines
The half-duplex timer command is used to tune half-duplex timers. With these timer tuning commands you can adjust the timing of the half-duplex state machines to suit the particular needs of their half-duplex installation.
You can configure more than one option using this command, but each option must be specified as a separate command.
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Note The half-duplex timer cts-delay command replaces the sdlc cts-delay command. The half-duplex timer rts-timeout command replaces the sdlc rts-timeout command. |
Value Ranges
The range of values for the cts-delay and rts-timeout keywords are dependent on the serial interface hardware.
Examples
The following example set the cts-delay timer to 10 ms and the transmit-delay timer to 50 ms:
Router(config)# interface serial 2 Router(config-if)# half-duplex timer cts-delay 10 Router(config-if)# half-duplex timer transmit-delay 50
Related Commands
Places a low-speed serial interface in controlled-carrier mode, instead of constant-carrier mode. Specifies the mode of a slow-speed serial interface on a router as either synchronous or asynchronous.
Command
Description
To limit the size of the IP output queue on an interface, use the hold-queue interface configuration command. To restore the default values for an interface, use the no form of this command with the appropriate keyword.
hold-queue length {in | out}
Syntax Description
length Integer that specifies the maximum number of packets in the queue. The range of allowed values is 0 to 65535. in Specifies the input queue. The default is 75 packets. For asynchronous interfaces the default is 10 packets. out Specifies the output queue. The default is 40 packets. For asynchronous interfaces the default is 10 packets.
Defaults
The default input hold-queue limit is 75 packets.
The default output hold-queue limit is 40 packets.
For asynchronous interfaces the default is 10 packets.
These limits prevent a malfunctioning interface from consuming an excessive amount of memory. There is no fixed upper limit to a queue size.
Command Modes
Interface configuration
Command History
10.0 This command was introduced. 11.1 The no hold-queue command was added.
Release
Modification
Usage Guidelines
The default of 10 packets allows the Cisco IOS software to queue a number of back-to-back routing updates. This is the default for asynchronous interfaces only; other media types have different defaults.
The hold queue stores packets received from the network that are waiting to be sent to the client. It is recommended that the queue size not exceed ten packets on asynchronous interfaces. For most other interfaces, queue length should not exceed 100.
The input hold queue prevents a single interface from flooding the network server with too many input packets. Further input packets are discarded if the interface has too many input packets outstanding in the system.
If priority output queueing is being used, the length of the four output queues is set using the priority-list global configuration command. The hold-queue command cannot be used to set an output hold queue length in this situation.
For slow links, use a small output hold-queue limit. This approach prevents storing packets at a rate that exceeds the transmission capability of the link. For fast links, use a large output hold-queue limit. A fast link may be busy for a short time (and thus require the hold queue), but can empty the output hold queue quickly when capacity returns.
To display the current hold queue setting and the number of packets discarded because of hold queue overflows, use the EXEC command show interfaces.
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Caution Increasing the hold queue can have detrimental effects on network routing and response times. For protocols that use seq/ack packets to determine round trip times, do not increase the output queue. Dropping packets instead informs hosts to slow down transmissions to match available bandwidth. This is generally better than having duplicate copies of the same packet within the network (which can happen with large hold queues). |
Examples
The following example sets a small input queue on a slow serial line:
Router(config)# interface serial 0 Router(config-if)# hold-queue 30 in
Related Commands
Displays statistics for all interfaces configured on the router or access server.
Command
Description
To allow the router to support a CSU/DSU that uses the LC signal to request a loopback from the router, use the hssi external-loop-request interface configuration command. To disable the feature, use the no form of this command.
hssi external-loop-requestSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
The HSA applique (on the HSSI) contains an LED that indicates the LA, LB, and LC signals transiting through the devices. The CSU/DSU uses the LC signal to request a loopback from the router. The CSU/DSU may want to do this so that its own network management diagnostics can independently check the integrity of the connection between the CSU/DSU and the router.
Use this command to enable a two-way, internal, and external loopback request on HSSI from the CSU/DSU.
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Caution If your CSU/DSU does not support this feature, it should not be enabled in the router. Not enabling this feature prevents spurious line noise from accidentally tripping the external loopback request line, which would interrupt the normal data flow. |
Examples
The following example enables a CSU/DSU to use the LC signal to request a loopback from the router:
Router(config-if)# hssi external-loop-request
To convert the HSSI interface into a clock master, use the hssi internal-clock interface configuration command. To disable the clock master mode, use the no form of this command.
hssi internal-clockSyntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
10.0 This command was introduced.
Release
Modification
Usage Guidelines
Use this command in conjunction with the HSSI null-modem cable to connect two Cisco routers together with HSSI. You must configure this command at both ends of the link, not just one.
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Note HSSI network module provides full-duplex connectivity at Synchronous Optical Network (SONET) OC-1/STS-1 (51.840 Mhz), T3 (44.736 MHz), and E3 (34.368 MHz) rates in conformance with the EIA/TIA-612 and EIA/TIA-613 specifications. The actual rate of the interface depends on the external data service unit (DSU) and the type of service to which it is connected. |
Examples
The following example converts the HSSI interface into a clock master:
Router(config-if)# hssi internal-clock
Syntax Description
ethernet Indicates that the hub is in front of an Ethernet interface. number Hub number, starting with 0. Because there is only one hub, this number is 0. port Port number on the hub. On the Cisco 2505 router, port numbers range from 1 to 8. On the Cisco 2507 router, port numbers range from 1 to 16. If a second port number follows, then the first port number indicates the beginning of a port range. end-port (Optional) Last port number of a range.
Defaults
No hub ports are configured.
Command Modes
Global configuration
Command History
10.3 This command was introduced.
Release
Modification
Usage Guidelines
There is not a no form of this command.
Examples
The following example enables port 1 on hub 0:
Router# hub ethernet 0 1 Router(config-hub)# no shutdown
The following example enables ports 1 through 8 on hub 0:
Router# hub ethernet 0 1 8 Router(config-hub)# no shutdown
Related Commands
Shuts down a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.
Command
Description
To configure the serial interface to monitor the DSR signal (instead of the DCD signal) as the line up/down indicator, use the ignore-dcd interface configuration command. To restore the default, use the no form of this command.
ignore-dcdSyntax Description
This command has no arguments or keywords.
Defaults
The serial interface, operating in DTE mode, monitors the DCD signal as the line up/down indicator.
Command Modes
Interface configuration
Command History
11.0 This command was introduced.
Release
Modification
Usage Guidelines
This command applies to Quad Serial NIM interfaces on the Cisco 4000 series routers and Hitachi-based serial interfaces on the Cisco 2500 and 3000 series routers.
Serial Interfaces in DTE Mode
When the serial interface is operating in DTE mode, it monitors the Data Carrier Detect (DCD) signal as the line up/down indicator. By default, the attached DCE device sends the DCD signal. When the DTE interface detects the DCD signal, it changes the state of the interface to up.
SDLC Multidrop Environments
In some configurations, such as an SDLC multidrop environment, the DCE device sends the Data Set Ready (DSR) signal instead of the DCD signal, which prevents the interface from coming up. Use this command to tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator.
Examples
The following example configures serial interface 0 to monitor the DSR signal as the line up/down indicator:
Router(config)# interface serial 0 Router(config-if)# ignore-dcd
To disable the monitoring of the LL pin when in DCE mode, use the ingnore-hw local-loopback interface configuration command. To return to the default, use the no form of this command.
ignore-hw local-loopbackSyntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Interface configuration
Command History
11.3 This command was introduced.
Release
Modification
Usage Guidelines
Use this command if your system is experiencing spurious modem interrupts, which momentarily causes the interface to enter loopback mode. The end result of this behavior is the loss of SDLLC sessions.
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Note This command only works with the low-speed serial interfaces. |
Examples
The following example displays how to disable the monitoring of the LL pin when in DCE mode:
Router#conf term Router(config)#interface serial 2
To configure an interface type and enter interface configuration mode, use the interface global configuration command.
interface type number [name-tag] Cisco 7200 Series and Cisco 7500 Series with a Packet over SONET Interface Processor
interface type slot/port
Cisco 7500 Series with Ports on VIP Cards
interface type slot/port-adapter/port [ethernet | serial]
Cisco 7500 Series with Channelized T1 or E1
interface serial slot/port:channel-group
Cisco 4000 Series with Channelized T1 or E1 and the Cisco MC3810
interface serial number:channel-group
To configure a subinterface, use this form of the interface global configuration commands:
Cisco 7500 Series with Ports on VIP Cards
interface type slot/port-adapter/port.subinterface-number [multipoint | point-to-point]
Cisco 7200 Series
interface type slot/port.subinterface-number [multipoint | point-to-point]
Cisco 7500 Series
interface type slot/port-adapter.subinterface-number [multipoint | point-to-point]
Syntax Description
Type of interface to be configured. See Table 12. number Port, connector, or interface card number. On a Cisco 4000 series router, specifies the NPM number. The numbers are assigned at the factory at the time of installation or when added to a system, and can be displayed with the show interfaces command. name-tag (Optional) Specifies the logic name to identify the server configuration so that multiple entries of server configuration can be entered. This optional argument is for use with the RLM feature. slot Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information. port Number of the port being configured. Refer to the appropriate hardware manual for slot and port information. port-adapter Number of the port-adapter being configured. Refer to the appropriate hardware manual for information about port adapter compatibility. ethernet Ethernet IEEE 802.3 interface. serial Serial interface. :channel-group Cisco 4000 series routers specify the T1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command. On a dual port card, it is possible to run channelized on one port and primary rate on the other port. Cisco MC3810 specifies the T1/E1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command. .subinterface-number Subinterface number in the range 1 to 4294967293. The number that precedes the period (.) must match the number to which this subinterface belongs. multipoint | point-to-point (Optional) Specifies a multipoint or point-to-point subinterface. There is no default.
Defaults
No interface types are configured.
Command Modes
Global configuration
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Note To use this command with the RLM feature, you must be in interface configuration mode. |
Command History
10.0 This command was introduced for the Cisco 7000 series routers. 11.0 This command was introduced for the Cisco 4000 series routers. 12.0(3)T The following optional argument was added for the RLM feature:
Release
Modification
Usage Guidelines
There is no correlation between the number of the physical serial interface and the number of the logical LAN Extender interface. These interfaces can have the same or different numbers.
| Keyword | Interface Type |
|---|---|
async | Port line used as an asynchronous interface. |
atm | ATM interface. |
bri | Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI). This interface configuration is propagated to each of the B channels. B channels cannot be individually configured. The interface must be configured with dial-on-demand commands in order for calls to be placed on that interface. |
dialer | Dialer interface. |
ethernet | Ethernet IEEE 802.3 interface. |
fastethernet | 100-Mbps Ethernet interface on the Cisco 4500, Cisco 4700, Cisco 7000, and Cisco 7500 series routers. |
fddi | Fiber Distributed Data Interface (FDDI). |
group-async | Master asynchronous interface. |
hssi | High-Speed Serial Interface (HSSI). |
lex | LAN Extender (LEX) interface. |
Software-only loopback interface that emulates an interface that is always up. It is a virtual interface supported on all platforms. The interface-number is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces you can create. | |
null | Null interface. |
port-channel | Port channel interface |
pos | Packet OC-3 interface on the Packet over SONET Interface Processor |
serial | Serial interface. |
switch | Switch interface |
tokenring | Token Ring interface. |
tunnel | Tunnel interface; a virtual interface. The number is the number of the tunnel interface that you want to create or configure. There is no limit on the number of tunnel interfaces you can create. |
vg-anylan | 100VG-AnyLAN port adapter |
There is not a no form of this command.
Examples
The following example configures serial interface 0 with PPP encapsulation:
Router(config)# interface serial 0 Router(config-if)# encapsulation ppp
The following example enables loopback mode and assigns an IP network address and network mask to the interface. The loopback interface established here will always appear to be up:
Router(config)# interface loopback 0 Router(config-if)# ip address 131.108.1.1 255.255.255.0
The following example for the Cisco 7500 series router shows the interface configuration command for Ethernet port 4 on the EIP that is installed in (or recently removed from) slot 2:
Router(config)# interface ethernet 2/4
The following example begins configuration on the Token Ring interface processor in slot 1 on port 0 of a Cisco 7500 series routers:
Router(config)# interface tokenring 1/0
The following example shows how a partially meshed Frame Relay network can be configured. In this example, subinterface serial 0.1 is configured as a multipoint subinterface with three Frame Relay PVCs associated, and subinterface serial 0.2 is configured as a point-to-point subinterface.
Router(config)# interface serial 0 Router(config-if)# encapsulation frame-relay Router(config)# interface serial 0.1 multipoint Router(config-if)# ip address 131.108.10.1 255.255.255.0 Router(config-if)# frame-relay interface-dlci 42 broadcast Router(config-if)# frame-relay interface-dlci 53 broadcast Router(config)# interface serial 0.2 point-to-point Router(config-if)# ip address 131.108.11.1 255.255.0 Router(config-if)# frame-relay interface-dlci 59 broadcast
The following example configures circuit 0 of a T1 link for Point-to-Point Protocol (PPP) encapsulation:
Router(config)# controller t1 4/1 Router(config-controller)# circuit 0 1 Router(config)# interface serial 4/1:0 Router(config-if)# ip address 131.108.13.1 255.255.255.0 Router(config-if)# encapsulation ppp
The following example configures LAN Extender interface 0:
Router(config)# interface lex 0
Related Commands
Resets the hardware logic on an interface. Configures a T1 or E1 controller and enters controller configuration mode. Sets the MAC layer address of the Cisco Token Ring. ppp Starts an asynchronous connection using PPP. Displays the statistical information specific to a serial interface. shutdown (RLM) Shuts down all of the links under the RLM group. slip Starts a serial connection to a remote host using SLIP.
Command
Description
Posted: Wed Mar 22 07:37:07 PST 2000
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